Research Of Gas-liquid Mixture Flow Characteristics Through Choke And Its Application

There are great difference in designing the throttling parameters between Water-bearing gas wells and dry gas wells. The flow of the gas liquid-mixture through the choke is regard as a polytropic process in this paper. Based on the energy equation, the new model has been established that gas-liquid mixture flow through the throttle. According to the characteristics of the throttling adiabatic, the computing model of the specific heat at constant pressure, constant volume specific heat and adiabatic exponent of gas mixture have been established. On this basis, considering on liquid production of gas wells and prevention of hydrate formation, coupling the computing models of wellbore pressure with Water-bearing gas well and wellbore temperature based on wellbore radial thermal conduction, those models have been built which are wellbore pressure and temperature model and throttling pressure drop model and temperature drop model and hydrate formation conductions forcasting model under the corresponding pressure and temperature. Comprehending all the models established, the choke size and setting depth can be computed. The software of optimized design of downhole choking is compiled by using visual basic program language to analyze the throttling sensitive factors impacting gas production and compare the gas-liquid model and dry gas model. It is thought that the largest gas production shows a downward trend with the increase of gas-liquid ratio when the other conditions remain invariant. Gas-liquid model and dry gas model are respectively applied to the gas field to design downhole throttling parameters, the calculation results show that the optimized design model of gas-liquid mixture through choke proposed is more accord with the actual situation of downhole choking in low permeability gas field, with the value of promotion and application.